A reinterpretation of Volcano Ranch lateral distribution measurements to infer the mass composition of cosmic rays

Abstract

In the course of its operation, the Volcano Ranch array collected data on the lateral distribution of showers produced by cosmic rays at energies above 10¹⁷ eV. From these data very precise measurements of the steepness of the lateral distribution function, characterized by the η parameter, were made. The current availability of sophisticated hadronic interaction models has prompted a reinterpretation of the measurements. We use the interaction models QGSJET and SIBYLL in the AIRES Monte Carlo code to generate showers together with GEANT4 to simulate the response of the detectors to ground particles. As part of an effort to estimate the primary mass composition of cosmic rays at this energy range, we present the results of our preliminary analysis of the distribution of η.